Color stabilization of fatty materials



COLOR STABILIZATION F MATERIALS Paul .Gibson,;C:hicago, 1111., :assignonto Swift & .Company,

Chicago, -Ill., ,acorporation .of Illinois No Drawing. Application January 7, 1957 Serial No. 632,639

6 Claims. (Cl.;26.0398.5)

The present invention relates to a method :of stabilizing the color of fatty materials.

The use of solvents and adsorbents to remove color impurities from fatty oils and fatty acids is-well known to the prior art. It has been found, for-example, that certain liquefied, normally gaseous hydrocarbons such as propane, ethane, and butane are capable-of removing color impurities from many types of fatty' materials. One of the adsorbents most Widely used in bleaching fats and oils is bleaching clay or fullers earth. This substance evidences an aflinity for pigments which are dissolved or dispersed inthe fats or oils. Activated carbon is often used along with bleaching clay to increase the effectiveness of the adsorbent under certain conditions. Color improvement is also imparted to fats and oils by the so-called alkali refining process, as well as by treating the product with certain common organic solvents such as acetone and methyl ethyl ketones.

Where liquefied, normally gaseous hydrocarbons are employed, the decolorization process essentially comprises dissolving the fatty material under pressure in several volumes of the hydrocarbon maintained at elevated temperatures. The solvent hydrocarbon preferentially dissolves certain portions of the fat which causes several phases -to form. The lighter or upper phases are substantially decolorized whereas the heavier or lower phases contain color bodies and tarry impurities. The upper phase or phases are removed and the hydrocarbon is separated from the fatty material by distillation to produce a decolorized product.

After the decolorization step, certain fats and fatty acids such as tallow, stearic acid, lauric acid, myristic acid, palmitic acid, and the like have a pronounced tendency to darken and revert to their original color when kept hot and exposed "to air. Although normal fat antioxidants are sometimes useful in preventing color reversion, they do not solve this problem in most instances. This ineffectiveness of antioxidants apparently lies 'in'the fact that oxidation plays but a minor role in color reversion processes.

One of the most effective materials which heretofore has been used to inhibit color reversion is hypophosphorous acid. When this chemical is added to fats either prior to their being decolorized or subsequent to the idecolorization step, the product is found to possess substantially improved color stability properties. The use of hypophosphorous acid for this purpose is described in United States Patent No. 2,673,868. Even hypophosphorous acid, however, has not been completely satisfactory in certain applications. Its limitations are especially demonstrated in commercial operations where the fat is held at high temperatures for long periods of time. 7

It is, therefore, an object of the present invention to 2 provide a method for stabilizing fatty materials against color reversion. I

Another object of the invention is to provide a method for stabilizing fatty materials against color reversion, which does not cause hypophosphorous .acid to lose its effectiveness under high temperature conditions.

Additional objects not specifically set forth herein will :become readily .apparent to one skilled in the .art from the following detailed description of the invention.

The present invention, in general, is based on the discovery thathypophosphorousacid can besubstantially improved .as'a'color stabilization material when this product is combined with certain other chemicals. More particularly, it has been found that the addition to hypophosphorous acid ,ofa compound taken from the group consisting of di-tertiary-butyl-para-cresol, butylated hydroxy anisole, betanaphthol, propyl gallate, and hydroquinone, contributes an unexpected synergistic eifect to the color stabilization properties of .H PO

The concentration :of the hypophosphorous acid-hydroxy benzene mixture added to the fatty stock should be from about two-hundredths (-0.02) of one (1.0) percent to about two (2.0) percent .by weight of the fatty material. In practice, the hypophosphorous acid may conveniently be added to the decolorized fat'prior to 'IhG addition=of the :hydroxy benzene component. This addition can either be .manually performed or the T131 0 can he sent :through a proportioning pump or the .like into the decolorizedtproduct before .or after it leaves the decolorizing tank. If it .is desired, the HgPO can be premixed with the hydroxy benzene compound prior to their introduction into the fat. The amount of H RO used in the method can vary from about one-hundredth (0.01) of one (1.0) percent to one (1.0) percent .or more by weight of the fatty stock. Similarly, as little as onehundredth (0.01) of one (1.0) percent of the particular hydroxy benzene material Will be beneficial in retaining the color stabilization properties of H PO The fatty materials to which the components are added should be kept about 10 to 30 F. above the temperature at which they are completely liquid (about -l70 F., depending on the particular fat being treated). Ordinarily, decolorized :oils after processing are kept at temperatures above which they are fluid only long enough to allow them to be pumped to storage tanks or tank cars. In many instances, however, the fats andoils are kept at elevated temperatures for several hours or more. in candle making, for example, it is necessary to maintain the fatty acids in a liquid state in order to allow the fat to be molded into desired configurations. Similarly, many industries maintain the fats and fatty acids in a liquid condition to increase .the ease with which they can be handled. Under such circumstances, it has been found that .those materials treated with hypophosphorous acid alone have a marked tendency to .color revert. This tendency is substantially eliminated when the H 'PO is used along with particular hydroxy benzene compounds.

The following examples illustrate the use of the present invention instabilizing the 'color of decolorized fats and oils.

Example I Five-tenths (0.5) of a gram of hypophosphorous acid was added with agitation to fifty (50) grams of propane decolorized liquid stearic acid. Twenty-five hundred-tbs (0.25) of a gram of di-tertiary-butyl-para-cresol was then added to the mixture. The high temperature color stability of stearic acid treated with the above materials was compared with a control amount of stearic'acid and with stearic acid treated with di-tertiary-bu'tyl-paracresol and hypophosphorous acid individually. The following results were obtained:

As is apparent from the above results, the combined use of hypophosphorous acid and di-tertiary-butyl-para-cresol contributed a significant synergistic effect which was not in evidence when the two chemicals were used separately. This improvement became more marked the longer the fat was held at high temperatures.

The color of the various fat samples was determined by matching them against standards provided by the Fat Analysis Committee of the American Oil Chemists Society and by comparing them with the 1933 Gardner color standards in the usual manner.

Example I! Stearic acid was treated with bleaching clay (fullers earth) and activated carbon at a temperature of about 180 F. to 220 F. After the acid was sufficiently lightened in color it was filtered through a bleaching press to remove the earth and carbon. One-tenth (0.1) of one (1.0) percent by weight of H PO was then added to the bleached fatty stock, and the material was filtered a second time. The fatty acid was then directed to a holding tank where one-tenth (0.1) of one (1.0) percent by weight of ditertiary-butyl-para-cresol was added. After a short holding period, the fatty stock was sent over a cold roller where it was solidified in the form of flakes. Subsequently, the fatty stock was liquefied and was held at 300 F. for twenty-four hours. At this time the material retained a FAC color rating of 1 and a Gardner color rating of 1. A control sample of this decolorized material and a sample which contained one-tenth (0.1) of one 1.0) percent H PO had FAC color ratings of 7 and 9, respectively, when held under identical conditions.

Example 111 The following hydroxy benzene compounds were subst-ituted for di-tertiary-butyl-para-cresol in the method set forth in Example 11:-

0.1% butylated hydroxy anisol and 0.1% H IO 0.1% beta naphthol and 0.l% H PO 0.1% propyl gallatc and 0.1% H PO 0.1% hydroquinone and 0.1% H PO Each of these materials demonstrated a synergistic effect with hypophosphorous acid which was comparable to that shown by di-tertiary-butyl-para-cresol.

Example IV A mixture consisting of seventy (70) percent propane decolorized stcaric acid and thirty (30) percent propane decolorized palmitic acid was treated with one-tenth (0.1) of one (1.0) percent H PO and one-tenth (0.1) of one (1.0) percent propyl gallate. After a holding period of twenty-four hours at 300 F., the material had a FAC color of 1. A control sample held under identical conditions had a color rating of PAC 5.

The present invention is considered applicable to both naturally occurring and hydrogenated saturated fatty acids and to all fats and oils which have a saturated fatty acid radical content of over fifty (50) percent. Fatty acids and fatty materials of this type are typified by stearic acid, myristic acid, palmitic acid, lauric acid, beef tallow, hydrogenated marine oils, etc.

Although the upper limit of the H PO -hydroxy benzene concentration range has been set at two (2.0) percent, the actual limit will be determined by economic considerations. The use of greater amounts of the stabilizer than two (2.0) percent would not decrease its efficiency.

The manner in which the fats and fatty acids are decolorized is not of critical importance and should not be considered as a limiting factor in the application.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. The method of inhibiting color reversion in decolorized fatty materials which comprises incorporating in the fatty materials a minor amount, no less than about 0.01%, of hypophosphorous acid and a minor amount, no less than about 0.01%, of a member taken from the group consisting of di-tertiary-butyl-para-cresol, butylated hydroxy anisole, beta naphthol, propyl gallate, and hydroquinone.

2. The method of inhibiting color reversion in decolorized fatty materials which comprises incorporating in the fatty materials from about one-hundredth (0.01) of one (1.0) percent to about one (1.0) percent by weight of hypophosphorous acid and from about one-hundredth (0.01) of one (1.0) percent to about one (1.0) percent by weight of a member taken from the group consisting of di-tertiary-butyl-para-cresol, butylated hydroXy anisole, beta naphthol, propyl gallate, and hydroquinone.

3. A method as in claim 1, wherein the fatty material is stearic acid.

4. A method as in claim 1, wherein the fatty material is palmitic acid.

5. A method as in claim 1, wherein the fatty material is a mixture of stearic and palmitic acids.

6. A new color stabilizer for decolorized fatty materials which comprises from about ten (10) percent to about ninety percent of hypophosphorous acid and from about ten (10) percent to about ninety (90) percent of a member taken from the group consisting of di-tertiary-butyl-para-cresol, butylated hydroXy anisole, beta naphthol, propyl gallate, and hydroquinone.

References Cited in the file of this patent UNITED STATES PATENTS 

1. THE METHOD OF INHIBITING COLOR REVERSION IN DECOLORIZED FATTY MATERIALS WHICH COMPRISES INCORPORATING IN THE FATTY MATERIALS A MINOR AMOUNT, NO LESS THAN ABOUT 0.01%, OF HYPOPHOSPHOROUS ACID AND A MINOR AMOUNT, NO LESS-THAN ABOUT 0.01%, OF A MEMBER TAKEN FROM THE GROUP CONSISTING OF DI-TERTIARY-BUTYL-PARA-CRESOL, BUTYLATED HYDROXY ANISOLE, BETA NAPHTHOL, PROPYL GALLATE, AND HYDROQUINONE. 